Mechanical stoker



INVENTOR 9e ATTORNEY 3 Sheets-Sheet 1 Cf. Ml Iler hm mw m 1 Apnl 1927 c. F. MlLLER MECHANICAL STOKER Filed Sept. 18, 1923 Apnl 1927' v c. E. MILLER MECHANICAL STOKER Filed Sept. 18, 1925 3 Sheets-Sheet 2 6'. E Miller INVENTOR ATTORNEY April 12, 1927.

C.F MHLER MECHANICAL STOKER 3 Sheets-Sheet 5 Filed Sept. 18. 1925 "(L E N's;

WITN S ATTORNEY Patented Apr. 12, 1927.

ers, particularly for driving ect to prov1de UNlTED STATES PATENT OFFICE.

RE, PENNSYLVANIA, ASSIGNOR T WESTINGHOUSE ELEC- ING COMPANY, A CORPORATION OF PENNSYLVANIA.

MECHANICAL STOKER.

Application filed September 18, 1923. Serial No. 663,436.

invention relates to mechanical stokto reciprocating engines the same, and it has for an obapparatus of the character designated which shall operate etlieiently hich shall discharge fuel to the furt an even and uniform rate of speed throughout the entire portion of the stroke.

It has for a further object to associate with the engine a governing mechanism by means of which.the desired stoker ly mal made scripti operating speed of the may be easily procured and accuratentained.

These and other objects, which will be apparent throughout the further deon of the invention may be attained by the employment of the apparatus hereinafter described and illustrated in the accompanying drawings in which Fig. 1 is a view in sectional elevation taken on the line I-I of Fig. 2 of a stoker engine of the type in which my invention may be practiced;

Fig. 2 is a transverse sectional elevation taken on the line 11-11 of Fig. 1 and Fig.

' 3 is a plan in section taken on the line IIIIII of Fig. 1 and der and cylinder covers of my with all associated parts showing the cylin stolrer engine removed.

Referring to the drawings for a detailed description of my invention, I show a power cylinder 10 provided with a front head 11 and a power wh 1ch through the rear Disposed within the cylinder 10 is a power piston 13 to is secured a piston rod 14 extending head 12 for driving the rear head 12.

ram of the stoker (not shown). For preventing leakage of steam between the rear cylinder head 12 and stuffing box tion is provided.

the piston rod 14, a 15 of any well known construc- The front cylinder head 11 is provided with a steam inlet 25 which communicates wlth a steam chest 26. Convalve 29 is a D to the steam chest 26 through a recar opening 27 is a transversely discylindrical housing 28 within which vided a main valve 29. The main slide valve and is adapted to reciprocate longitudinally with respect to the ho using. Angular displacement is prevented by a guide screw 31 which slidably engages a groove 32 the length of the valve.

in the mg 28 on eac extending throughout Centrally disposed lower portion of the main valve housis an exhaust port 33, and, provided h side of the exhaust port, are steam ports 34 and 35. The exhaust port 33 communicates directly with a main exhaust passage 36 provided with an outlet connection 37. The steam ports 34 and 35 communicate respectively with passages 38 and 39, provided in the front cylinder head 11, and passages 40 and 41 provided in the power cylinder casting 10. The passage 40 terminates near the front end of the cylinder while the passage 41 terminates near the rear end. A plurality of rectangular ports 42 and 42 and relatively smaller cylindrical ports 43 and 43 communicate with the passages 40 and 41 for the admission of steam to and the exhausting of steam from the respective ends of the power cylinder. A drain connection 44 is located in each of the passages 40 and 41 for the removal of any condensate which may accumulate therein. Sultable dram-cocks 45 are provlded.

The main valve 29 is actuated by two pistons 51 and 51 provided within the cylindrical housing 28. The two pistons 51 and 51 are rigidly connected by a spindle 52 having a central portion of reduced diameter 53. That portion of the spindle having the smaller diameter is arranged within the groove 32 provided in the main valve 29 and the shoulder formed on the spindle serves to move the valve in unison with the pistons 51 and 51. The pistons 51 and 51 are in turn moved by steam acting upon their outer faces, the supply of steam being controlled by a pilot valve 54. The pilot valve 54 is of the D-slide type, and is arranged within a cylindrical bored housing 55 which is disposed in axial alignment with the cylinder 10 and which freely communicates with the steam chest 26. Centrally disposed in the lower portion of the pilot valve housing 55 is an exhaust port 56 and provided on each side of the exhaust port 56 are steam ports 57 and 58. The exhaust port 56 communicates through a passage 59 with the main exhaust passage 36. The steam ports 57 and 58 communicate through respective passages 61 and 62 with the bore of the main valve housing 28, whereby the supply of steam to and the exhaust of steam from the ends of the housing are controlled by the movements of the pilot valve 54 in such manner as to reciprocate the pistons 51 and 51' and the main valve 29.

The pilot valve 54 is moved mechanically by the power piston 13 and the piston rod 14. It is secured to a valve rod 71 which freely moves in an axial direction in bearings 72 and 73 provided in the front cylinder head'll. The valve rod 71 is provided with a portion 74 having a reduced diameter, which portion is arranged within a groove 75 extended throughout the length of the pilot valve. This construction causes the pilot valve to move with the valve rod. An-

gular displacement of the pilot valve 54 isv prevented by a pin 76 which slidably engages the groove 75. The rear portion of the valve rod 71 is housed within a hollow portion 77 of the piston rod 14, and it is provided with an enlarged end portion 78. The power piston 13 is provided with a stop member 79 which alternately engages, near the end of each stroke, the enlarged end portion 78 and a transverse surface 78 of the valve rod 71. As the steam pressure prevailing within the power cylinder 10 is present in the hollow portion 77 of the piston rod 14 and consequently exerts a thrust upon the rear transverse surface of the valve rod 71, a passage 81 is provided for maintaining an equal pressure of steam upon the forward transverse face of the rod, thereby permitting free and unbiased axial movement of the pilot valve 54.

Arranged in axial alignment with the valve rod 71 is a reversing pin 85. This may, by manual operation, be moved into engagement with the valve rod 71 to move the pilot valve 54. This procedure reverses the direction of movement of the power piston 13 during any portion of the fuel-feeding stroke, that is, the movement of the piston from the front to the rear end of the cylinder. The steam pressure prevailing within the cylinder, which is present in the space intervening between the valve rod 71 and the reversing pin 85, tends to maintain the latter in spaced relation to the valve rod during normal operation of the engine. To prevent leakage of steam around the reversing pin, astulfing box 86 is provided which is equipped with a gland 87 and packing 88. A guard 91. having a suitable access opening 92 provided therein, surrounds the reversing pin for protecting the same from injury.

For adjusting and for governing the speed of the stoker engine, plungers 95 and 96 are provided. They are secured to the pistons 51 and 51, respectively, and extend into hydraulic chambers 97 and 98 which are arranged in axial alignment with the main valve housing 28 and which may be secured to the frontcylinder cover 11 by any suitable means. Communicating means between the hydraulic chambers is through a conduit 99. Arranged in the conduit 99 is a valve 100 preferably of the needle type, by means of which very accurate adjustments or small alterations of the flow area may be made. A dial 101 together with a pointer 102 may be associated with the valve for indicating to what extent it is opened or closed. The conduit 99 communicates through a T fitting 103 with a conduit 10A for supplying fluid to the hydraulic chambers 97 and 98. The conduit 104 in turn connects with a reservoir 105, which is cast integral with the front head 11 of the power cylinder, and which is so formed as to maintain therein a constant storage of excess condensate which is utilized to com aensate for losses of the liquid which may be incurred in the operation of the engine. The reservoir communicates through a cored passage 106, with the steam chest 26. For preventing a back-flow of water from the hydraulic chambers into the steam chest 26, a check valve 107 is provided in the conduit 104. For preventing leakage of water from the hydraulic chambers into the main valve housing 28 a ring 108 together with a plurality of packing elements 109 are provided.

The operation of the above apparatus is as follows: Upon steam under pressure being admitted to the inlet connection 25, it fills the steam chest 26 and flows through the rectangular opening 27 into the main valve housing 28, wherein it is confined within the space intervening between the pistons 51 and 51, and tends to hold the main valve against its seat. The steam also flows upwardly through the passage 106, and enters the reservoir 105 and the conduit 104. It passes through the check valve 107 and, upon entering the T fitting 103, is separated into two portions and flows respectively through the conduits 99, the needle valve 100 being in open position, to the hydraulic chambers 97 and 98. The steam is confined therein by means of the packing elements 109. and, upon an accumulation of pressure equivalent to that of the supply, the flow ceases. The hydraulic chambers 97 and 98, the conduits 99 and 104 and the reservoir 105 being subject to the relatively cool temperature of the surrounding atmosphere, the steam contained therein is rapidly condensed by radiation, whereupon additional steam immediately enters until such time as the h y draulic chambers together with their communicating conduits and the storage rescrvoir are entirely filled with water. Thereafter, any loss of condensate which may occur incident to the operation of the engine is automatically made up by the motive steam supplying means.

Steam from the steam chest 26 enters the pilot valve housing 55 and tends to hold the valve 54 against its seat. Should the valve be in the position illustrated in Fig. 1, the steam is permitted to flow through the passage 61 to one end of the main valve housing 28, wherein it acts upon the outer face of the piston 51 and causes the same, to-

gether with the main valve 29 and the piston 51', to be moved to the opposite end of the housing 28, that is, the position illustrated in Fig. 2. Upon such a movement of the main valve 29, the steam, which as aforesaid is maintained under pressure within the confines of the pistons 51 and 51', enters the uncovered steam port 34 and flows through the passage 38 to a communicating passage 40 provided in the power cylinder 10, and shown in Fig. 3. It then flows through the cylindrical ports 43 to the bore of the power cylinder 10, wherein it acts upon the front face of the power piston 13, causing the same to move toward the rear of the cylinder. Upon the steam ports 42 becoming uncovered, additional motive steam enters the power cylinder to assist the piston to complete what may be termed the fuel-feeding stroke.

Upon the movement of the main valve 29, as described above, the plunger 96 enters the hydraulic chamber 98 and displaces a quantity of the water contained therein.

( This water enters the communicating conduit 99 and compels an equivalent amount of water to enter the hydraulic chamber 98, the plunger 95 having receded therefrom coincident with the movement of the plunger 96. The area of flow through the communicating conduit 99 may, by the employment of the needle valve 100, be so varied as to alter the time required to pass the required amount of water through the restricted opening and thereby accurately control the speed of movement of the main valve 29 and incidentally the speed of the engine. I have found from experiment that with my governing device, the 'desired operating speed of the engine may be easily and accurately obtained, and that the desired speed is thereafter automatically maintained irrespective of ordinary fluctuations in 'the pressure of the motive steam. Furthermore, the movement of the power piston throughout its entire stroke is very smooth and uniform, the jerkiness or unsteady movements generally inherent in apparatus of this character being absent.

Shortly before the power piston 13 reaches the full extent of its fuel-feeding stroke, the stop member 7 9 associated therewith engages the enlarged end portion on 78 of the valve rod 71 and moves it forward. The extent of the movement is sufficient to cause the pilot valve 54 to cover the steam port 57, thereby shutting off the supply of steam to the piston 51, uncover the port 58 and place the steam port 57 in communication with the exhaust port 56. This permits the steam to flow through the passage 62 to one end of the main valve housing 28 and to act upon the outer face of the piston 51, thereby moving it to the opposite end of the valve chamber. It also permits the steam which is present in the opposite end of the main valve chamber to be exhausted through the passage 61, ports 57 and 56, and the passage 59 to the main exhaust passage 36. to that displaced by the plunger 95 is compelled to pass through the needle valve 100, the speed of movement of the main valve 29 is'dependent upon the prior setting of that valve, that is, upon the amount of time required for the water to pass through the restricted opening which may be formed therein.

Upon the main valve 29 moving to the opposite end of the chamber, the steam port 34 becomes covered and subsequently the steam port is uncovered and the steam port 34 placed in communication with the exhaust port 33. Steam, which is present in the main valve chambers 28 between the pistons 51 and 51, flows through the pars sage 39 to the communicating passage 41 provided in the power cylinder 10, whereupon it flows through the ports 43 and 42 and acts upon the rear face of the power piston 13 to move the same to the front end of the cylinder. The exhaust steam which is present on the opposite face of the power piston 13 passes out through the passages and 38 to the ports 34 and 33 and thence to the main exhaust passage 36 from where it is discharged through the outlet connection 37 Upon the power piston 13 approaching the front cylinder head 11, the stop member 79 engages the transverse face 78' of the valve rod 71 and moves the pilot valve 54 to restart the cycle of operation.

If during any portion of the fuel-feeding stroke, the piston 13 is stalled in its rearward movement due to a jamming of some foreign substance in the fuel, the reversing pin may be manually brought into contact with the valve rod 71, causing the pilot valve 54 to be moved to its rear position and incidentally operating the main valve 29 to reverse the direction of flow of the motive steam to the power cylinder 10, whereupon the power piston 13 travels to the front end of the cylinder and then reverses its motion in the usual way.

Apparatus constructed as above described, provides a very efficient and compact form of engine for driving a mechanical stoker. Especially desirable is the form of hydraulic governing means employed, not only because of the results obtained. but also because of the fact that the fluid employed is identical with that used in the power cylinder. The two fluids being the same, a con stant supply of the working fluid is always present in the governing mechanism during the operation of the stoker, no care or attention whatever on the part of the operator As an amount of water equivalent with respect to this portion of the apparatus 1 being required.

lVhile I have shown my invention in but one form, it will be obvious to those skilled in the art that it is not so limited, but is susceptible of various other changes and modifications, without departing from the spirit thereof, and I desire, therefore, that only such limitations shall be placed thereupon as are imposed by the prior art or as are specifically set forth in the appended claims.

lVhat I claim is:

1. In a Stoker engine, in combination, a power cylinder, a valve for controlling the supply of motive steam to the cylinder, means for operating said valve, hydraulic chambers operatively associated with the valve for governing the movements of the same, means for supplying steam to the engine, means for condensing a quantity of said steam and for delivering the condensate to the hydraulic chambers, and means for preventing a back-flow of the condensate into the steam supply means.

2. In a stoker engine, in combination, :1 power cylinder, a piston disposed therein, ahead portion for the cylinder having providcd therein a cylindrically-bored housing, a pair of pistons disposed within the housing, a valve for controlling the supply of motive steam to the power cylinder interposed between and secured to the piston, means for supplying steam under pressure between the pistons, means for actuating the valve by alternately supplying steam to and exhausting steam from the outer surfaces of the respective pistons, a plunger connected to each piston, hydraulic chamber for each plunger, communicating means between the hydraulic chambers, and means for conveying a quantity of condensed steam to each of the hydraulic chambers, whereby coincident with the movements of the valve, a plunger displaces a quantity of condensed steam in one hydraulic chamber and discharges through the communicating means an equal quantity of condensed steamto the remaining hydraulic chamber.

In testimony whereof, I have hereunto subscribed my name this 13th day of Sept. 1923.

CHARLES F. MILLER. 

